Target Heart Rate & Cardio Zones Calculator
Calculate your age-predicted maximum heart rate, resting reserve, and precise 5-zone workout intensity targets.
Optimal intensity for mitochondrial biogenesis, aerobic capacity building, and maximal lipid substrate oxidation.
5 Heart Rate Training Zones (ACSM Protocol)
Calculated using the Karvonen Heart Rate Reserve formula for your baseline conditioning:
| Zone | Intensity % | Target BPM | Primary Benefit | Main Fuel Source |
|---|---|---|---|---|
| Zone 1: Active Recovery | 50% – 60% | 125 – 137 BPM | Recovery, warm-up, cellular blood flow | 85% Fats / 15% Carbs |
| Zone 2: Aerobic Base / Fat Burn | 60% – 70% | 137 – 150 BPM | Mitochondrial density, endurance base | 65% Fats / 35% Carbs |
| Zone 3: Tempo / Aerobic Power | 70% – 80% | 150 – 162 BPM | Cardiovascular efficiency, pace sustainability | 45% Fats / 55% Carbs |
| Zone 4: Lactate Threshold | 80% – 90% | 162 – 175 BPM | Lactate clearance, high-speed tolerance | 20% Fats / 80% Carbs |
| Zone 5: VO2 Max / Anaerobic Peak | 90% – 100% | 175 – 187 BPM | Peak sprint power, fast-twitch recruitment | 5% Fats / 95% Glycogen |
Cardio & Heart Rate FAQs
What is Target Heart Rate (THR)?
Target Heart Rate is the desired cardiovascular beats per minute (BPM) range to maintain during exercise to stimulate specific physiological adaptations, such as mitochondrial biogenesis, maximal fat oxidation (Zone 2), or lactate threshold buffering (Zone 4).
Why is the Tanaka formula preferred over the traditional 220 - Age rule?
The traditional Fox formula (220 - Age) was derived from small anecdotal samples in 1971 and substantially underestimates maximum heart rate in older adults and overestimates it in younger populations. The Tanaka formula (208 - 0.7 × Age), published in JACC in 2001 from a meta-analysis of 18,712 subjects, provides significantly higher statistical accuracy across all age groups.
What is the Karvonen Heart Rate Reserve (HRR) formula?
The Karvonen formula accounts for your baseline cardiovascular fitness by incorporating your Resting Heart Rate (RHR). By calculating the difference between your Max HR and Resting HR (the Heart Rate Reserve), it provides a personalized training target that reflects your actual aerobic conditioning level.
What is Zone 2 training and why is it popular?
Zone 2 (60%–70% of Heart Rate Reserve) is the aerobic intensity zone where lipid (fat) oxidation is maximized and blood lactate levels remain baseline (~1.5–2.0 mmol/L). It builds foundational cardiovascular endurance and enhances mitochondrial density without overstressing the nervous system.
Scientific References & Peer-Reviewed Literature
- Tanaka H, Monahan KD, Seals DR. (2001). Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology, 37(1), 153–156. PMID: 11153730.
- Gellish RL, Goslin BR, Olson RE, et al. (2007). Longitudinal modeling of the relationship between age and maximal heart rate. Medicine & Science in Sports & Exercise, 39(5), 822–829. PMID: 17468781.
- Karvonen MJ, Kentala E, Mustala O. (1957). The effects of training on heart rate; a longitudinal study. Annales Medicinae Experimentalis et Biologiae Fenniae, 35(3), 307–315. PMID: 13470504.
- American College of Sports Medicine (ACSM). (2021). ACSM's Guidelines for Exercise Testing and Prescription. 11th edition. Wolters Kluwer.
